Hibernate_03(一对多和多对多)

本文详细介绍了Hibernate中一对多及多对多关系映射的方法,包括如何通过配置文件实现关联关系,解决性能问题,以及多对多关系下中间表的设计与使用。

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/**
 * 回顾:
 * 		表数据和表数据之间可以存在的关系?
 * 			建立关系的好处:对于多表查询关系数据的时候
 * 		一对多:
 * 			原则:在多的一方建立一个字段当成外键,指向一的一方的主键
 * 		多对多:
 * 			在外部创建一张中间表,让这个中间表中至少有2个字段分别指向各自表的主键
 * 		一对一:
 * 			让各自表的主键字段当成外键,指向另一张表的主键
 * Hibernate是怎么做一对多的关系映射?
 * 		例如:客户与联系人
 * 		 	在一的一方有多的一方的集合
 * 			在多的一方有一的一方的对象
 * 			(请看代码...)
 * 		当运行的测试,在保存一个客户和一个联系人的过程中,发现有2条insert语句,和一条update语句
 * 		虽然update语句不影响程序,但影响了性能
 * 		要想这些sql语句(update)能不能就不要出现了..
 * 		解决方案:
 * 			因为2方都维护了外键;让其中一方放弃不在维护外键即可
 * 			inverse让外键失效
 * 			<set name="linkmans" inverse="true" cascade="save-update">
 *				<key column="lkm_cust_id"></key>
 *				<one-to-many class="xinfei.code.domain.Linkman"/> 
 *			</set>
 * 
 * Hibernate是怎么做多对多的关系映射?
 * @author zx
 *
 */

hibernate.cfg.xml配置

<?xml version="1.0" encoding="UTF-8"?>

<!-- 约束可以在hibernate-core-5.0.7.Final.jar->org.hibernate倒数dtd约束大概10行 -->
<!DOCTYPE hibernate-configuration PUBLIC
	"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
	"http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
	<session-factory>
		<!-- 配置数据库的信息 ps:去hibernate-release-5.0.7.Final\project\etc\hibernate.properties -->
		<!-- 配置mysql驱动 -->
		<property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
		<!-- 配置mysql数据库地址 -->
		<property name="hibernate.connection.url">jdbc:mysql:///hibernate</property>
		<!-- 配置mysql数据库的用户名 -->
		<property name="hibernate.connection.username">root</property>
		<!-- 配置mysql数据库的密码 -->
		<property name="hibernate.connection.password">root</property>
		<!-- 配置方言 告诉hibernate生成的sql数符合我当前数据库的sql语句 例子: 分页 mysql: select * from 
			表 limit ?,? sqlserver: select * from 表 top ?,? oracle: 自己手写sql嵌套 -->
		<property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
		<!-- 为hibernate配置c3p0 -->
		<property name="hibernate.connection.provider_class">org.hibernate.connection.C3P0ConnectionProvider</property>
		<!-- 为了让hibernate生成的sql语句在控制台显示出来 -->
		<property name="hibernate.show_sql">true</property>
		<!-- 为了让显示的sql语句格式化好看点 -->
		<property name="hibernate.format_sql">true</property>

		<!-- 配置让hibernate根据映射关系给自动生成数据库的表 默认是不生成的 取值: create:没有表创建表,有表了删除表在创建 create-drop:没有表创建表,有表了删除表在创建 
			用完再删 update: 用它 没有表创建表 有表使用表 validate: 默认值 不让hibernate创建 -->
		<property name="hibernate.hbm2ddl.auto">update</property>
		<!-- 引入映射文件地址 -->
		<mapping resource="xinfei/code/domain/Customer.hbm.xml" />
		<mapping resource="xinfei/code/domain/Linkman.hbm.xml" />
		<mapping resource="xinfei/code/domain/User.hbm.xml" />
		<mapping resource="xinfei/code/domain/Role.hbm.xml" />
	</session-factory>
</hibernate-configuration>
domain实体

package xinfei.code.domain;

import java.util.HashSet;
import java.util.Set;

/**
 * 客户表 一对多的关系 一个客户可以对应多个联系人
 * 
 * @author zx
 *
 */
public class Customer {
	public Long cust_id;// '客户编号(主键)',
	public String cust_name;// '客户名称(公司名称)',
	public String cust_source;// '客户信息来源',
	public String cust_industry;// '客户所属行业',
	public String cust_level;// '客户级别',
	public String cust_phone;// '固定电话',
	public String cust_mobile;// '移动电话',

	private Set<Linkman> linkmans = new HashSet<Linkman>();

	public Customer() {
		super();
	}

	public Set<Linkman> getLinkmans() {
		return linkmans;
	}

	public void setLinkmans(Set<Linkman> linkmans) {
		this.linkmans = linkmans;
	}

	public Long getCust_id() {
		return cust_id;
	}

	public void setCust_id(Long cust_id) {
		this.cust_id = cust_id;
	}

	public String getCust_name() {
		return cust_name;
	}

	public void setCust_name(String cust_name) {
		this.cust_name = cust_name;
	}

	public String getCust_source() {
		return cust_source;
	}

	public void setCust_source(String cust_source) {
		this.cust_source = cust_source;
	}

	public String getCust_industry() {
		return cust_industry;
	}

	public void setCust_industry(String cust_industry) {
		this.cust_industry = cust_industry;
	}

	public String getCust_level() {
		return cust_level;
	}

	public void setCust_level(String cust_level) {
		this.cust_level = cust_level;
	}

	public String getCust_phone() {
		return cust_phone;
	}

	public void setCust_phone(String cust_phone) {
		this.cust_phone = cust_phone;
	}

	public String getCust_mobile() {
		return cust_mobile;
	}

	public void setCust_mobile(String cust_mobile) {
		this.cust_mobile = cust_mobile;
	}

	@Override
	public String toString() {
		return "Customer [cust_id=" + cust_id + ", cust_name=" + cust_name + ", cust_source=" + cust_source
				+ ", cust_industry=" + cust_industry + ", cust_level=" + cust_level + ", cust_phone=" + cust_phone
				+ ", cust_mobile=" + cust_mobile + "]";
	}

}
package xinfei.code.domain;

/**
 * 联系人表
 * 
 * @author zx
 *
 */
public class Linkman {
	private Long lkm_id;// '联系人编号(主键)',
	private String lkm_name;// '联系人姓名',
	private String lkm_gender;// '联系人性别',
	private String lkm_phone;// '联系人办公电话',
	private String lkm_mobile;// '联系人手机',
	private String lkm_email;// '联系人邮箱',
	private String lkm_qq;// '联系人qq',
	private String lkm_position;// '联系人职位',
	private String lkm_memo;// '联系人备注',

	private Customer customer;

	public Linkman() {
		super();
	}

	public Long getLkm_id() {
		return lkm_id;
	}

	public void setLkm_id(Long lkm_id) {
		this.lkm_id = lkm_id;
	}

	public String getLkm_name() {
		return lkm_name;
	}

	public void setLkm_name(String lkm_name) {
		this.lkm_name = lkm_name;
	}

	public String getLkm_gender() {
		return lkm_gender;
	}

	public void setLkm_gender(String lkm_gender) {
		this.lkm_gender = lkm_gender;
	}

	public String getLkm_phone() {
		return lkm_phone;
	}

	public void setLkm_phone(String lkm_phone) {
		this.lkm_phone = lkm_phone;
	}

	public String getLkm_mobile() {
		return lkm_mobile;
	}

	public void setLkm_mobile(String lkm_mobile) {
		this.lkm_mobile = lkm_mobile;
	}

	public String getLkm_email() {
		return lkm_email;
	}

	public void setLkm_email(String lkm_email) {
		this.lkm_email = lkm_email;
	}

	public String getLkm_qq() {
		return lkm_qq;
	}

	public void setLkm_qq(String lkm_qq) {
		this.lkm_qq = lkm_qq;
	}

	public String getLkm_position() {
		return lkm_position;
	}

	public void setLkm_position(String lkm_position) {
		this.lkm_position = lkm_position;
	}

	public String getLkm_memo() {
		return lkm_memo;
	}

	public void setLkm_memo(String lkm_memo) {
		this.lkm_memo = lkm_memo;
	}

	public Customer getCustomer() {
		return customer;
	}

	public void setCustomer(Customer customer) {
		this.customer = customer;
	}

	@Override
	public String toString() {
		return "Linkman [lkm_id=" + lkm_id + ", lkm_name=" + lkm_name + ", lkm_gender=" + lkm_gender + ", lkm_phone="
				+ lkm_phone + ", lkm_mobile=" + lkm_mobile + ", lkm_email=" + lkm_email + ", lkm_qq=" + lkm_qq
				+ ", lkm_position=" + lkm_position + ", lkm_memo=" + lkm_memo + ", customer=" + customer + "]";
	}

}
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC 
    "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
    "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
	<class name="xinfei.code.domain.Customer" table="cst_customer">
		<id name="cust_id" column="cust_id">
			<generator class="native"></generator>
		</id>
		<property name="cust_name" column="cust_name"></property>
		<property name="cust_source" column="cust_source"></property>
		<property name="cust_industry" column="cust_industry"></property>
		<property name="cust_level" column="cust_level"></property>
		<property name="cust_phone" column="cust_phone"></property>
		<property name="cust_mobile" column="cust_mobile"></property>
		<!-- 建立客户和联系人的一对多关系 name:是多的一方集合对象 inverse:让外键失效 cascade:级联配置 save-update:级联保存值 
			delete:级联删除值 即级联保存又级联删除:save-update,delete lazy: true:延迟加载(默认);false:立即加载 -->
		<set lazy="false" name="linkmans" inverse="true" cascade="save-update,delete">
			<!-- 外键的字段名 -->
			<key column="lkm_cust_id"></key>
			<!-- 对方的全限定名 -->
			<one-to-many class="xinfei.code.domain.Linkman" />
		</set>
	</class>
</hibernate-mapping>    
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC 
    "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
    "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">

<hibernate-mapping>
	<class name="xinfei.code.domain.Linkman" table="cst_linkman">
		<id name="lkm_id" column="lkm_id">
			<generator class="native"></generator>
		</id>
		<property name="lkm_name" column="lkm_name"></property>
		<property name="lkm_gender" column="lkm_gender"></property>
		<property name="lkm_phone" column="lkm_phone"></property>
		<property name="lkm_mobile" column="lkm_mobile"></property>
		<property name="lkm_email" column="lkm_email"></property>
		<property name="lkm_qq" column="lkm_qq"></property>
		<property name="lkm_position" column="lkm_position"></property>
		<property name="lkm_memo" column="lkm_memo"></property>
		<!-- 建立客户和联系人的一对多关系 Customer customer many-to-one: 在多的一方做一对多关系建立的 name: 
			在自己里面一的一方对象属性名 class: 一的一方的全限定名 column:外键的字段名称 -->
		<many-to-one cascade="save-update" name="customer"
			class="xinfei.code.domain.Customer" column="lkm_cust_id"></many-to-one>
	</class>
</hibernate-mapping>
一对多测试

package xinfei.code.test;

import org.hibernate.Session;
import org.hibernate.Transaction;
import org.junit.Test;

import xinfei.code.domain.Customer;
import xinfei.code.domain.Linkman;
import xinfei.code.utils.HibernateUtils;

public class MoreToOneTest {
	
	@Test
	/**
	 * 创建一对多的表关系
	 */
	public void test01(){
		Session openSession = HibernateUtils.openSession();
	}
	
	@Test
	//保存第一个客户与联系人
	public void test02(){
		Session session = HibernateUtils.openSession();
		//开启事务
		Transaction transaction = session.beginTransaction();
		Customer customer = new Customer();
		customer.setCust_name("刘总");
		Linkman linkman = new Linkman();
		linkman.setLkm_name("联系人_01");
		customer.getLinkmans().add(linkman);
		linkman.setCustomer(customer);
		session.save(customer);
		session.save(linkman);
		transaction.commit();
		session.close();
	}
	
	/**
	 * 保存一个用户和多个联系人
	 */
	@Test
	public void test03(){
		Session session = HibernateUtils.openSession();
		Transaction transaction = session.beginTransaction();
		//创建一个用户
		Customer customer = new Customer();
		customer.setCust_name("马总");
		//创建多个联系人
		Linkman linkman01 = new Linkman();
		linkman01.setLkm_name("一对多-客服_01号");
		Linkman linkman02 = new Linkman();
		linkman02.setLkm_name("一对多-客服_02号");
		Linkman linkman03 = new Linkman();
		linkman03.setLkm_name("一对多-客服_03号");
		Linkman linkman04 = new Linkman();
		linkman04.setLkm_name("一对多-客服_04号");
		//客户保存联系人
		customer.getLinkmans().add(linkman01);
		customer.getLinkmans().add(linkman02);
		customer.getLinkmans().add(linkman03);
		customer.getLinkmans().add(linkman04);
		//联系人保存用户
		linkman01.setCustomer(customer);
		linkman02.setCustomer(customer);
		linkman03.setCustomer(customer);
		linkman04.setCustomer(customer);
		//保存用户
		session.save(customer);
		//保存联系人
		session.save(linkman01);
		session.save(linkman02);
		session.save(linkman03);
		session.save(linkman04);
		//提交
		transaction.commit();
		session.close();//关闭
	}
	
	/**
	 * 级联保存.保存客户的时候就把联系人保存了
	 */
	@Test
	public void test04(){
		Session session = HibernateUtils.openSession();
		Transaction transaction = session.beginTransaction();
		//创建一个用户
		Customer customer = new Customer();
		customer.setCust_name("邓总");
		//创建多个联系人
		Linkman linkman01 = new Linkman();
		linkman01.setLkm_name("一对多级联保存-客服_01号");
		Linkman linkman02 = new Linkman();
		linkman02.setLkm_name("一对多级联保存-客服_02号");
		Linkman linkman03 = new Linkman();
		linkman03.setLkm_name("一对多级联保存-客服_03号");
		Linkman linkman04 = new Linkman();
		linkman04.setLkm_name("一对多级联保存-客服_04号");
		//客户保存联系人
		customer.getLinkmans().add(linkman01);
		customer.getLinkmans().add(linkman02);
		customer.getLinkmans().add(linkman03);
		customer.getLinkmans().add(linkman04);
		//联系人保存用户
		linkman01.setCustomer(customer);
		linkman02.setCustomer(customer);
		linkman03.setCustomer(customer);
		linkman04.setCustomer(customer);
		//保存用户
		session.save(customer);
		/**
		 * 当在保存用户的时候,hibernate配置
		 * cascade:
		 * 	级联配置 save-update:级联保存值  delete:级联删除值 即级联保存又级联删除:save-update,delete
		 */
		//提交
		transaction.commit();
		session.close();//关闭
	}
	/**
	 * 测试删除数据
	 */
	@Test
	public void test05(){
		Session session = HibernateUtils.openSession();
		Transaction transaction = session.beginTransaction();
		//创建一个用户
		Customer customer = new Customer();
		customer.setCust_name("级联删除");
		//创建多个联系人
		Linkman linkman01 = new Linkman();
		linkman01.setLkm_name("测试删除数据-一对多级");
		Linkman linkman02 = new Linkman();
		linkman02.setLkm_name("测试删除数据-一对多级");
		Linkman linkman03 = new Linkman();
		linkman03.setLkm_name("测试删除数据-一对多级联");
		Linkman linkman04 = new Linkman();
		linkman04.setLkm_name("测试删除数据-一对多级联");
		//客户保存联系人
		customer.getLinkmans().add(linkman01);
		customer.getLinkmans().add(linkman02);
		customer.getLinkmans().add(linkman03);
		customer.getLinkmans().add(linkman04);
		//联系人保存用户
		linkman01.setCustomer(customer);
		linkman02.setCustomer(customer);
		linkman03.setCustomer(customer);
		linkman04.setCustomer(customer);
		//保存用户
		session.save(customer);
		//提交
		transaction.commit();
		session.close();//关闭
	}
	
	/**
	 * 删除,把一个用户删除了
	 */
	@Test
	public void delTest06(){
		Session session = HibernateUtils.openSession();
		Transaction transaction = session.beginTransaction();
		Customer customer = session.get(Customer.class,4L);
		session.delete(customer);
		transaction.commit();
		session.close();
	}
	
	/**
	 * 删除,级联删除
	 */
	@Test
	public void delTest07(){
		Session session = HibernateUtils.openSession();
		Transaction transaction = session.beginTransaction();
		/**
		 * 级联删除,需要hibernate配置
		 * cascade:
		 * 	级联配置 save-update:级联保存值  delete:级联删除值 
		 * 	即级联保存又级联删除:save-update,delete
		 */
		Customer customer = session.get(Customer.class,4L);
		session.delete(customer);
		transaction.commit();
		session.close();
	}
}
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

package xinfei.code.domain;

import java.util.HashSet;
import java.util.Set;

public class Role {
	private Long role_id;// 主键
	private String role_name;// '角色名称',
	private String role_memo;// '备注',

	private Set<User> users = new HashSet<User>();//用户集合

	public Role() {
		super();
	}

	public Long getRole_id() {
		return role_id;
	}

	public void setRole_id(Long role_id) {
		this.role_id = role_id;
	}

	public String getRole_name() {
		return role_name;
	}

	public void setRole_name(String role_name) {
		this.role_name = role_name;
	}

	public String getRole_memo() {
		return role_memo;
	}

	public void setRole_memo(String role_memo) {
		this.role_memo = role_memo;
	}

	public Set<User> getUsers() {
		return users;
	}

	public void setUsers(Set<User> users) {
		this.users = users;
	}

	@Override
	public String toString() {
		return "Role [role_id=" + role_id + ", role_name=" + role_name + ", role_memo=" + role_memo + ", users=" + users
				+ "]";
	}

}
package xinfei.code.domain;

import java.util.HashSet;
import java.util.Set;

public class User {
	private Long user_id;// '用户id',
	private String user_code;// '用户账号',
	private String user_name;// '用户名称',
	private String user_password;// '用户密码',
	private String user_state;// '1:正常,0:暂停',

	private Set<Role> roles = new HashSet<Role>();// 角色集合

	public User() {
		super();
	}

	public Long getUser_id() {
		return user_id;
	}

	public void setUser_id(Long user_id) {
		this.user_id = user_id;
	}

	public String getUser_code() {
		return user_code;
	}

	public void setUser_code(String user_code) {
		this.user_code = user_code;
	}

	public String getUser_name() {
		return user_name;
	}

	public void setUser_name(String user_name) {
		this.user_name = user_name;
	}

	public String getUser_password() {
		return user_password;
	}

	public void setUser_password(String user_password) {
		this.user_password = user_password;
	}

	public String getUser_state() {
		return user_state;
	}

	public void setUser_state(String user_state) {
		this.user_state = user_state;
	}

	public Set<Role> getRoles() {
		return roles;
	}

	public void setRoles(Set<Role> roles) {
		this.roles = roles;
	}

	@Override
	public String toString() {
		return "User [user_id=" + user_id + ", user_code=" + user_code + ", user_name=" + user_name + ", user_password="
				+ user_password + ", user_state=" + user_state + ", roles=" + roles + "]";
	}

}
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC 
    "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
    "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
	<class name="xinfei.code.domain.Role" table="sys_role">
		<id name="role_id" column="role_id">
			<generator class="native"></generator>
		</id>
		<property name="role_name" column="role_name"></property>
		<property name="role_memo" column="role_memo"></property>
		<set name="users" table="sys_user_role" inverse="true">
			<key column="role_id"></key>
			<many-to-many class="xinfei.code.domain.User" column="user_id"></many-to-many>
		</set>
	</class>
</hibernate-mapping>
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC 
    "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
    "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
	<class name="xinfei.code.domain.User" table="sys_user">
		<id name="user_id" column="user_id">
			<generator class="native"></generator>
		</id>
		<property name="user_code" column="user_code"></property>
		<property name="user_name" column="user_name"></property>
		<property name="user_password" column="user_password"></property>
		<property name="user_state" column="user_state"></property>
		<!-- 建立多对多的关系 设置集合 private Set<Role> roles name:集合名称 table:要生成的中间表表名称 -->
		<set name="roles" table="sys_user_role">
			<!-- 自己在中间表的外键字段名 -->
			<key column="user_id"></key>
			<!-- class: 对方的全限定名 column: 对方在中间表的外键字段名称 -->
			<many-to-many class="xinfei.code.domain.Role" column="role_id"></many-to-many>
		</set>
	</class>
</hibernate-mapping>
package xinfei.code.test;

import org.hibernate.Session;
import org.hibernate.Transaction;
import org.junit.Test;

import xinfei.code.domain.Customer;
import xinfei.code.domain.Role;
import xinfei.code.domain.User;
import xinfei.code.utils.HibernateUtils;

public class MaryToMaryTest {

	/**
	 * 多对多测试数据
	 * 需求:保存2个用户,3个角色
	 */
	@Test
	public void test01(){
		Session session = HibernateUtils.openSession();
		Transaction transaction = session.beginTransaction();
		//创建两个用户
		User user01 = new User();
		user01.setUser_name("多对多-用户01");
		User user02 = new User();
		user02.setUser_name("多对多-用户02");
		
		//创建3个角色
		Role role01 = new Role();
		role01.setRole_name("多对多-角色01");
		Role role02 = new Role();
		role02.setRole_name("多对多-角色02");
		Role role03 = new Role();
		role03.setRole_name("多对多-角色03");
		
		//做用户与角色关联
		user01.getRoles().add(role01);
		user01.getRoles().add(role02);
		user02.getRoles().add(role01);
		user02.getRoles().add(role03);
		//角色和用户关联
		role01.getUsers().add(user01);
		role01.getUsers().add(user02);
		role02.getUsers().add(user01);
		role03.getUsers().add(user02);
		
		//保存用户
		session.save(user01);
		session.save(user02);
		//保存角色
		session.save(role01);
		session.save(role02);
		session.save(role03);
		/**
		 * 当commit的时候,会报一个错,意思就是说其中一条已存在
		 * 原因:两张表都在维护,创建了相同的数据
		 * 解决:让一方放弃维护,(一般就是被动方放弃维护)
		 * 在Role.hbm.xml 配置 inverse="true"
		 * <set name="users" table="sys_user_role" inverse="true">
		 */
		transaction.commit();
		session.close();
	}
	
	/**
	 * 对于多对多关心是中间表的分配
	 * 给用户的CRUD
	 * 给用户添加一个角色
	 */
	@Test
	public void test02(){
		Session session = HibernateUtils.openSession();
		Transaction transaction = session.beginTransaction();
		//获取一个用户
		User user = session.get(User.class,1L);
		//获取一个角色
		Role role = session.get(Role.class,7L);
		//给这个用户添加获取这个角色
		user.getRoles().add(role);
		//持久态对象 只要修改了任意属性,会自动更新到数据库
		transaction.commit();
		session.close();
	}
	
	/**
	 * 删除一个角色
	 */
	@Test
	public void test03(){
		Session session = HibernateUtils.openSession();
		Transaction transaction = session.beginTransaction();
		//获取一个用户
		User user = session.get(User.class,1L);
		Role role = session.get(Role.class,8L);
		user.getRoles().remove(role);
		transaction.commit();
		session.close();
	}
	
	/**
	 * 修改一个用户角色
	 */
	@Test
	public void test04(){
		Session session = HibernateUtils.openSession();
		Transaction transaction = session.beginTransaction();
		//获取一个用户
		User user = session.get(User.class, 1L);
		Role role = session.get(Role.class, 6L);
		//
		Role update_role = session.get(Role.class,7L);
		user.getRoles().remove(role);
		user.getRoles().add(update_role);
		transaction.commit();
		session.close();
	}
	
	/**
	 * 对象导航查询
	 * 意思就是做查询的时候,不只会查询对象本身的数据,当对象中还有别的对象或集合的时候,会把里面对象或集合的数据也一并给查询出来
	 */
	@Test
	public void test05(){
		Session session = HibernateUtils.openSession();
		Transaction transaction = session.beginTransaction();
		Customer customer = session.get(Customer.class,1L);
		System.out.println("customer信息:" + customer.getLinkmans());
		transaction.commit();
		session.close();
	}
}
utils工具类

package xinfei.code.utils;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;

public class HibernateUtils {
	
	static Configuration configure = null;
	static SessionFactory sessionFactory = null;
	static{
		configure = new Configuration().configure();
		sessionFactory = configure.buildSessionFactory();
	}
	
	//获取session链接方法
	public static Session openSession(){
		return sessionFactory.openSession();
	}
	//从当前线程中获取session的方法
	public static Session getCurrentSession(){
		return sessionFactory.getCurrentSession();
	}
}
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